Medical Geology Studies on Tehran Map (1:100000 scale)
Tehran industrial and urban development has been so fast within the last tow decades, and it has brought several soil and water pollution. So, --------
A) Studying on Geochemistry and Pollution of Soil and Sediments
Since soil contamination and its direct or indirect influence on living things health is very important in different sectors This study has been carried out for understanding distribution of toxic elements (Hg, Pb, Cd, Sb, As, Al, Sn) with geogenic and anthropogenic origin. So, 43 samples were collected from urban soil (residential, agricultural, industrial, and recreational) and analysed with ICP-MS. Analytical data have been compared with soil standards of Canada and Australia.
Results showed the anomaly of heavy metals in Tehran surface soil. For gaining more information, it is nesessary to have detailed studies.
B) Studying Hydro-Geochemistry of Water Resources:
- Underground Water (wells & reservoirs):
GSI research team in cooperation with water and sewerage organization, has sampled groundwater in Tehran city in order to study the contaminating sources with geogenic and anthropogenic origin. Totally, 175 water samples (122 wells, 53 drinking water reservoir) were collected and were sent to the laboratory of Tehran water and sewerage organization for studying physical and chemical parameters (alkalinity, hardness, Nitrate and nitrite, toxic elements …).
The results show the higher concentration of Na, Mg, Mn, Fe, Zn, Co, Cr, NH4, SO4 and Cl in water resources in South of city. Consequently, total water hardness is more in these regions and needs more consideration in respect of kidney diseases and urine ducts.
The study indicates that the quality of drinking water resources in northern and western parts of city is higher due to special geological status, type of geologic formations and aquifer hydraulic and hydrogeologic features. Moving toward south eastern parts, the quality is lower, out it should be considered in determining the place of drilling new wells. A significant part of ground and deep water pollution comes from detergents, Nitrates, and nitrites. The nitrate concentration is more than 45 mg/L (standard limit) in most samples, due to urban sewerage. Heavy metals and toxic elements such as mercury, and Arsenic are also observed in samples.
C) Surficial Waters
Our research team, collected 157 surficial water samples (river, drainages, and springs) for 44 elemental ICP-MS analysis. The results were compared with standard of EPA and WHO. At last, the distribution maps of elements in surface waters were prepared in GIS system.
D) Studying on Natural Radionuclide in Water and Sediments
GSI Medical Geology Management in cooperation with Atomic energy organization studied on distribution of natural radionuclides in water and sediment of Tehran, Karaj and Shahriar. Totally 132 water samples were collected from surface waters and drinking water wells and reservoirs.
80 sediment samples were collected from 5cm depth.
samples were analyzed in Atomic Energy organization laboratory for measuring natural radionuclides 40K,226Ra, 232Th and 137Cs for sediments and 226Ra, 137Cs, 222Rn ,U total And β ، α emissions for water samples. The results were compared with EQGS Canada (2003) and EPA American standards.
The results indicates that 232Th in sediment sampels in comparisons with standard rates is normal but the average of 40K and 226Ra are greater than standard guideline value. Average amount of radionuclides is very close to each other in ground and surfacial water samples. Comparing the average concentration of this radionuclide with existing standards revealed that all measured samples are less than risk limit and aren't deemed as a threat.